Sundasciurus hippurus is most often seen in lowland primary forest but
has been found in re-grown logged forests and secondary forests. (Medway,1978;
Payne,1985). (Medway, 1978; Payne, J, et al., 1985)

Physical Description
Range mass
260 to 420 g
(9.16 to 14.80 oz)

Range length
21.5 to 25 cm
(8.46 to 9.84 in)

Sundasciurus hippurus is the largest and most colourful of the Sunda tree
squirrels, Sundasciurus, with considerable geographical colour variation in
Borneo. This medium-sized squirrel always has a grey head, shoulders, and fore
feet. This grey pelage may be more or less grizzled. The upperparts are reddish
brown to chestnut. Subspecies differ, the hind legs may be grey or reddish brown
and the underside is whitish, dull orange, or reddish brown. The tail is glossy
black or grey and black banded. Despite the common name, horse-tailed squirrel,
the tail is not very similar to that of a horse. There are some individuals
resembling Callosciurus erythraeus. But in northern Malaysia, where both
species occur, horse-tailed squirrels have uniform red undersides, not agouti,
and darker and more bushy tails. (Payne, 1985, Lekagul & McNeely, 1977 ; Medway,
1978 ; Corbet & Hill, 1992)

Very little is known about mating behavior and systems in Sundasciurus species.
Breeding season
These squirrels probably breed throughout the year.
Females have two or three pairs of mammae. Little is known of reproduction in
these squirrels but perhaps, as in other diurnal squirrels in that region, they
produce young throughout the year. Two close relatives, Sundasciurus lowii
and S. tenuis, have litter sizes of 2 to 4.

Key Reproductive Features
Iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes
separate); viviparous
Little is known of parental investment in these squirrels. Females care for and
nurse their offspring until independence in a tree nest.

Lifespan/Longevity

Status: captivity
14 (high) years
Lifespan is unknown in these squirrels. Most squirrel species have lifespan
averaging 3 to 7 years.

Behaviour

Horse-tailed squirrels are diurnal. They are solitary or occur in pairs (Medway,
1978) They feed and move mainly in the lower and middle part of the understory,
but nest in the upper canopy. Sometimes they came to the ground. In Malaysia
they share their habitat with Callosciurus notatus and Callosciurus
nigrovittatus in the same understory (8-18 m). Larger diurnal squirrels tend
to live in the upper canopy and smaller species from the ground level through
the lower canopy. (McKinnon, in McDonald, 2001). (McDonald David, 2001)Key Behaviours
arboreal ; diurnal ; sedentary ; solitary

Horse-tailed squirrels feed on seeds, fruits, and arthropods. In Malaysia they
are reported to feed on bark and sap, while sympatric beautiful squirrels
(Callosciurus species) feed more opportunistically on different plant material
and insects (McKinnon in McDonald, 2001). Like other squirrels, they may include
a diversity of foods in their diet, such as eggs, young vertebrates, and fungi.
(McDonald David, 2001; Nowak, 1997)Animal Foods
insects; terrestrial non-insect arthropodsPlant Foods
leaves; wood, bark, or stems; seeds, grains, and nuts; fruit; sap or other plant
fluids

Predation

Horse-tailed squirrels avoid predation primarily through their agility and
vigilance in the trees. Few predators can chase and capture adults the forest
canopy. Young squirrels are vulnerable to predation in the nest by small,
arboreal predators such as snakes, cats, or other squirrels. Their coloration
may make them cryptic in the forest canopy.

Ecosystem Roles

Horse-tailed squirrels are important seed dispersers in primary and secondary
lowland forests throughout their range. They may also serve as an important prey
base for large predators, such as raptors.

Ecosystem Impact
disperses seeds

Economic Importance for Humans: Positive

Horse-tailed squirrels may help to disperse the seeds of important lowland tree
species.
Economic Importance for Humans: Negative
There are no negative impacts of horse-tailed squirrels on humans.

Conservation Status

IUCN Red List of Threatened Species
Near Threatened
More Information
Horse-tailed squirrels have no special status, although they may be threatened
by habitat destruction throughout their range.